Performance data in the AFM/POH should be:

The performance data in the Aircraft Flight Manual (AFM) or Pilot Operating Handbook (POH) is typically established under standard atmospheric conditions, which are defined as a temperature of 15 degrees Celsius at sea level and a pressure of 29.92 inches of mercury. These conditions are often referenced as "standard" because the performance figures—such as takeoff distance, climb rate, and stall speed—are derived from tests conducted at these specific conditions.

When flying under actual operating conditions that differ from these "standard" conditions, it's essential to understand that the performance data might not directly represent what will occur in-flight. However, for numerous pilots, the AFM/POH provides baseline performance information that is relevant under standard conditions. Therefore, the idea that the performance figures "remain the same because adjustments have been made" directly reflects the expectation that pilots should be aware of how atmospheric variations influence aircraft performance while still trusting the performance data under those "standard" conditions.

Consideration of factors like altitude, temperature, and humidity—often referenced as non-standard atmospheric conditions—can significantly impact aircraft performance, so while the base figures from the AFM/POH don’t need continual adjustments for each flight, understanding their application under different conditions is crucial.